Present day automatic high production foundry installations utilize high pressure squeeze molding machines in a molding line to form cope and drag molds in respective flasks. The cope and drag molds are then cored, if necessary, and assembled to form complete foundry molds which are then placed on a pouring and cooling conveyor for casting. After the casting has cooled, the cope and drag flasks are punched out to remove the molding sand and casting therefrom, separated, and then recycled through the molding line.
In high production units for large size flasks, the molding lines may either be "in-line" or "cross-loop" systems. In a "cross-loop" system, the cope and drag molds are generally molded separately in parallel conveyor systems each crossing a loop of a pouring and cooling conveyor. In an "in-line" system, the molding line generally extends parallel to the pouring and cooling conveyor and the cope and drag flasks are conveyed through the molding line in alternating cope and drag flask sets. The molding machines are then next to each other on a single conveyor. Both "in-line" and "cross-loop" mold production units have been manufactured for many years by the Osborn Manufacturing Corporation of Cleveland, Ohio.
In conventional "in-line" molding systems, the flasks are driven through the molding line by a number of clutch and brake operated powered conveyor rolls which require relatively sophisticated and expensive controls so that each flask will be properly positioned for the variety of operations which must be performed thereon. Typically, the foundry mold with the cool casting therein is placed on the entrance of the molding line and after the casting and sand has been punched from the cope and drag flasks, such flasks are cleaned and separated. The cope and drag flasks are then driven into the cope and drag molding machines which conventionally include an elevating table which includes a pattern plate. The flasks are filled with sand and elevated against a squeeze board to form the pattern impression on the lower face of the mold thus formed in each flask. The flasks with the molds therein are then replaced on the molding line conveyor and moved therealong through a coring station and drag roll over station, the latter of which inverts the drag flask so that the pattern cavity in the drag mold face is facing upwardly. After coring and drag roll over, the cope and drag flasks with the molds therein are assembled with the cope mold on top and the drag mold on the bottom and then placed on the pouring and cooling conveyor.
For each of the above described operations, the cope and drag flasks must be relatively precisely centered and must be slightly spaced from each other to avoid interference. Accordingly, when a power driven conveyor is employed, the conveyor itself and particularly the controls for the drives can become inordinately expensive in addition to being a very high maintenance item.
It of course would be desirable if the sets of cope and drag flasks could be simply pushed through the molding line in abutting relationship; however, some means must be found to center and separate the flasks for each of the above noted operations. Moreover, when the flasks are again indexed by pushing, the slack or spacing between the flasks will be taken up, and like the last car on a railroad train, a flask may be subjected to a substantial jolt or bump when the slack is taken out of the line of flasks. This can cause damage or disintegration to a mold previously formed and can of course damage a flask. Accordingly, molding lines which employ abutting flasks pushed along an idler conveyor have numerous drawbacks which limit both productivity and reliability.
A foundry molding system overcoming many of the drawbacks associated with such molding lines is disclosed in the aforenoted U.S. Pat. No. 4,261,413. Such system has been successfully employed and provides desirable and advantageous results.
In particular, the foundry molding system disclosed in U.S. Pat. No. 4,261,413 includes a linear idler molding line conveyor adjacent a cooling conveyor. The molding line conveyor utilizes flanged idler rollers, such as those sold by the Osborn Manufacturing Corporation under the trademark LOAD RUNNER, which are journaled on stub shafts projecting inwardly from conveyor rails to support the cope and drag flasks on the flanged lower side edges thereof. Relatively short powered roller sections are provided at the entrance and exit ends of the idler roller section for flask disassembly and assembly in the set-off and closing operations described in such patent. As disclosed, a set-off removes the assembled cope and drag flasks from the cooling conveyor and forms them into horizontally abutting cope and drag flask sets on the molding line conveyor whereas a set-on at the other end of the molding line conveyor closes and sets the assembled cope and drag flasks with respective molds therein on the cooling conveyor.
Further in such system of U.S. Pat. No. 4,261,413, the cope and drag flask sets are controllably indexed along the molding line conveyor by indexing and control devices at opposite ends of the conveyor, each indexing step moving the flasks a distance slightly more than the horizontal length of a single set of cope and drag flasks. Positioned strategically along the molding line conveyor are opposed sets of power operated roller detents or locators which cooperate with horizontally spaced bars forming detent receptacles on each flask. Such locators separate and center the flasks for the various operations.
It further is noted that the set-off and set-on of such system each includes a vertically movable cope pick-up and a vertically movable drag pick-up which also is horizontally shiftable at right angles to the molding line conveyor and the adjacent cooling conveyor. The drag pick-up has pivoting lift arms adapted to engage and lift the top flange of the drag flask whereas the cope pick-up has L-shaped lift arms adapted to engage the top flange of the cope flask. During the closing operation, the cope flask is first moved into and picked up by the cope pick-up of the set-on, and then the short powered roller section associated with the set-on is operated to move the drag flask into the set-on. As the drag flask is then elevated by the drag pick-up, the drag mold therein is closed against the bottom of the cope mold in the cope flask and the thusly formed assembly is lifted off the cope pick-up arms a short distance and brought to bear against a stop to provide a controlled crush of the sand face between the cope and drag molds. Thereafter, the drag pick-up supporting the completed foundry mold is horizontally shifted above the cooling conveyor and lowered to place the mold onto the cooling conveyor. As the cope flask is coextensive with the cope pick-up arms during such horizontal shifting, the ends of the cope flask are recessed to clear the flange engaging portions of such arms.